EQUIRA was a phase III, double-blind study conducted in patients with moderate-to-severe rheumatoid arthritis and inadequate response to disease-modifying anti-rheumatic drugs. Eligible patients were randomized 1:1 to receive subcutaneous 50 mg SDZ ETN or ETN, once-weekly, for 24 weeks. At week 24, patients with at least moderate EULAR response in the SDZ ETN group continued SDZ ETN treatment, and those in the ETN group were switched to receive 50 mg SDZ ETN, for up to 48 weeks. Patients received concomitant methotrexate at a stable dose (10–25 mg/week) and folic acid (≥ 5 mg/week). Equivalence between SDZ ETN and ETN for change from baseline in disease activity score including 28 joint count C-reactive protein (DAS28-CRP) at week 24 (primary endpoint) and comparable safety and immunogenicity profile of SDZ ETN and ETN have previously been demonstrated at week 24. Herein, we present the 48-week results of the study after a single switch from ETN to its biosimilar at week 24.

Results

The least squares mean (standard error) change in DAS28-CRP from baseline up to week 48 was comparable between “continued SDZ ETN” (− 2.90 [0.12], n = 148) and “switched to SDZ ETN” (− 2.78 [0.13], n = 131) groups. The proportion of patients achieving EULAR good/moderate responses based on DAS28-erythrocyte sedimentation rate and ACR20/50/70 response rates were comparable between the two groups. The proportion of patients with at least one treatment-emergent adverse event was 42.9% in the “continued SDZ ETN” and 38.0% in the “switched to SDZ ETN” groups. Serious adverse events occurred in 4 patients in each of the two groups. After week 24, none of the patients in the switched group developed anti-drug antibodies (ADAs), while 4 patients in the continued SDZ ETN group had single-event, very low titer, non-neutralizing ADAs detected.

Conclusions

The 48-week results from the EQUIRA study demonstrate that switch from ETN to SDZ ETN in patients with moderate-to-severe rheumatoid arthritis does not impact the efficacy, safety, or immunogenicity of etanercept.